Using {memcpy,strncpy,strcpy,kstrdup} to copy the task comm relies on the
length of task comm. Changes in the task comm could result in a destination
string that is overflow. Therefore, we should explicitly ensure the
destination string is always NUL-terminated, regardless of the task comm.
This approach will facilitate future extensions to the task comm.
As suggested by Linus [0], we can identify all relevant code with the
following git grep command:
git grep 'memcpy.*->comm\>'
git grep 'kstrdup.*->comm\>'
git grep 'strncpy.*->comm\>'
git grep 'strcpy.*->comm\>'
PATCH #2~#4: memcpy
PATCH #5~#6: kstrdup
PATCH #7: strcpy
Please note that strncpy() is not included in this series as it is being
tracked by another effort. [1]
task_lock() is removed from get_task_comm() as it is unnecessary.
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psR30+CogFd4aXrThr2gsiS4g@xxxxxxxxxxxxxx/ [0]
Changes:
v8->v9:
- Keep the BUILD_BUG_ON() in get_task_comm() (Kees)
- Keep strscpy_pad() in get_task_comm() (Kees)
- Replace more strcpy() with strscpy() in
drivers/gpu/drm/i915/i915_gpu_error.c (Justin)
- Fix typos and commit improvement in patch #5 (Andy)
- Drop the change in net as it was fixed by
b19f69a95830 ("net/ipv6: replace deprecated strcpy with strscpy")
v7->v8: https://lore.kernel.org/all/20240828030321.20688-1-laoar.shao@xxxxxxxxx/
- Avoid '+1' and '-1' in string copy. (Alejandro)
v6->v7: https://lore.kernel.org/all/20240817025624.13157-1-laoar.shao@xxxxxxxxx/
- Improve the comment (Alejandro)
- Drop strncpy as it is being tracked by another effort (Justin)
https://github.com/KSPP/linux/issues/90 [1]
v5->v6: https://lore.kernel.org/linux-mm/20240812022933.69850-1-laoar.shao@xxxxxxxxx/
- Get rid of __get_task_comm() (Linus)
- Use ARRAY_SIZE() in get_task_comm() (Alejandro)
v4->v5: https://lore.kernel.org/all/20240804075619.20804-1-laoar.shao@xxxxxxxxx/
- Drop changes in the mm/kmemleak.c as it was fixed by
commit 0b84780134fb ("mm/kmemleak: replace strncpy() with strscpy()")
- Drop changes in kernel/tsacct.c as it was fixed by
commit 0fe2356434e ("tsacct: replace strncpy() with strscpy()")
v3->v4: https://lore.kernel.org/linux-mm/20240729023719.1933-1-laoar.shao@xxxxxxxxx/
- Rename __kstrndup() to __kmemdup_nul() and define it inside mm/util.c
(Matthew)
- Remove unused local variable (Simon)
v2->v3: https://lore.kernel.org/all/20240621022959.9124-1-laoar.shao@xxxxxxxxx/
- Deduplicate code around kstrdup (Andrew)
- Add commit log for dropping task_lock (Catalin)
v1->v2: https://lore.kernel.org/bpf/20240613023044.45873-1-laoar.shao@xxxxxxxxx/
- Add comment for dropping task_lock() in __get_task_comm() (Alexei)
- Drop changes in trace event (Steven)
- Fix comment on task comm (Matus)
v1: https://lore.kernel.org/all/20240602023754.25443-1-laoar.shao@xxxxxxxxx/
Yafang Shao (7):
Get rid of __get_task_comm()
auditsc: Replace memcpy() with strscpy()
security: Replace memcpy() with get_task_comm()
bpftool: Ensure task comm is always NUL-terminated
mm/util: Fix possible race condition in kstrdup()
mm/util: Deduplicate code in {kstrdup,kstrndup,kmemdup_nul}
drm: Replace strcpy() with strscpy()
drivers/gpu/drm/drm_framebuffer.c | 2 +-
drivers/gpu/drm/i915/i915_gpu_error.c | 6 +--
fs/exec.c | 10 -----
fs/proc/array.c | 2 +-
include/linux/sched.h | 28 +++++++++---
kernel/auditsc.c | 6 +--
kernel/kthread.c | 2 +-
mm/util.c | 62 ++++++++++++---------------
security/lsm_audit.c | 4 +-
security/selinux/selinuxfs.c | 2 +-
tools/bpf/bpftool/pids.c | 2 +
11 files changed, 63 insertions(+), 63 deletions(-)
--
2.43.5
